The next step is to date the paint pigments. If they are confirmed as being of similar age, this raises the real possibility that the paintings were the handiwork of Neanderthals — an “academic bombshell”, says Sanchidrian, because all other cave paintings are thought to have been produced by modern humans.

Neanderthals are in the frame for the paintings since they are thought to have remained in the south and west of the Iberian peninsula until approximately 37,000 years ago — 5000 years after they had been replaced or assimilated by modern humans elsewhere in their European heartland.